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J.R. Martin (University of Virginia Dept of Astronomy), J.E. Hibbard (National Radio Astronomy Observatory, Charlottesville), R.W. O'Connell (University of Virginia Dept of Astronomy)
The presence of gaseous merger histories in early type galaxies was tested through a detection survey of 21cm hydrogen emission in the environments of two samples of early type galaxies. The test sample consisted of early type galaxies with central spikes in their surface brightness profiles which may indicate a former dense star formation region. The control sample consisted of early type galaxies without central spikes (and presumably without as recent or as densely located star formation events) and covered a similar range of distances and sizes. Both samples were chosen to be free of dust and active galactic nuclei. The two samples (17 test galaxies and 19 controls) were observed with the Green Bank Telescope with the spectrometer. The spectra were reduced by removing the radio frequency inteference, calibrating via the noise diode and position switching, averaging the multi-integrated spectra, baselining, and calibrating the flux via the observation of a standard source (3C295). The spectra of three galaxies were contaminated by continuum sources in the beam. The spectra of nine more galaxies displayed one or more 21cm lines. Three of these galaxies are members of the test sample and 6 are controls. After comparing the positions and velocities of neighboring galaxies which may have contaminated the beam to the observed spectral features, the probability that environmental gas can be associated with early type galaxies with central spikes is slightly higher. However, the numbers are too low for an adequate statistical analysis and mapping may be required to determine better positions for the detected gas.
This work has been funded by NSF REU for NRAO's Summer Student Research Assistantship Program.
The author(s) of this abstract have provided an email address for comments about the abstract: jodie@virginia.edu
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.